1. Field of the Invention
The present invention relates to a thermally transcribing printer and an image forming apparatus, particularly relates to a thermally transcribing printer and an image forming apparatus including a roller for feeding sheet.
2. Description of the Related Art
In a background art, there is known an image forming apparatus of a thermally transcribing printer or the like including a roller for feeding sheet (refer to, for example, JP-UM-A-61-132344).
JP-UM-A-61-132344, mentioned above, discloses a structure in which a roll main body and a rotating shaft are fixed by fixing a stopper having an arm is fixed to the rotating shaft by inserting a pin into a pin inserting hole of the rotating shaft and engaging the arm of the stopper with an engaging hole of the roll main body at a portion of fixing the roll main body (roller) for feeding sheet and the rotating shaft attached with the roll main body.
FIG. 17 is a perspective view showing a total constitution of a thermally transcribing printer according to an example of a background art. FIG. 18 is a sectional view showing a structure of attaching a roller for feeding sheet of the thermally transcribing printer of the background art shown in FIG. 17 at constant speed. FIG. 19 is a perspective view showing a structure of attaching the roller shown in FIG. 18 to a gear. An explanation will be given of a structure of the thermally transcribing printer according to the example of the background art.
As shown by FIG. 17, the thermally transcribing printer apparatus of the background art includes a frame 101 made of a metal, a roller 102 made of a metal for feeding sheet at constant speed, a gear 103 made of a resin, a motor 104 for driving to rotate the gear, a motor bracket 105 made of a metal, a leaf spring 106 made of a metal, bearing members 107 and 108 (refer to FIG. 18) an ink sheet winding gear 109, a roller shaft drive gear 110, a plurality of middle gears 111, a sheet charging and discharging roller 112, a roller shaft 113 of the sheet charging and discharging roller 112, an ink sheet case 114, and a sheet bottom receiving guide 115. As shown by FIG. 18, a shaft portion 102a of one end of the roller 102 made of a metal for feeding sheet at constant speed is rotatably inserted into the bearing member 108 attached to one side face of the frame 101. Further, an oval shape portion 102b (refer to FIG. 19) formed at an outer side of the shaft portion 102a of the roller 102 is fitted to the gear 103. As shown by FIG. 19, the oval shape portion 102b of the roller 102 is machined in an oval shape and fitted to a fitting hole 103a in an oval shape of the gear 103. Thereby, the roller 102 and the gear 103 can be connected so as not to be rotated idly. Further, other end 102c of the roller 102 is rotatably inserted into the bearing member 107 attached to other side face of the frame 101. The motor 104 is attached to the motor bracket 105 made of a metal attached to the frame 101. The motor 104 functions as a drive source for driving the ink sheet winding gear 109 and the roller shaft drive gear 110. Further, as shown by FIG. 18, the leaf spring 106 made of a metal is fixed to the motor bracket 105 made of a metal. A movable end 106a of the leaf spring 106 is arranged to be brought into contact with a side face of the oval shape portion 102b of the roller 102. Thereby, the leaf spring 106 functions as the ground.
Next, an explanation will be given of operation of feeding sheet at constant speed of the thermally transcribing printer according to the example of the background art. As operation of feeding sheet at constant speed of the printer of the background art, as shown by FIG. 17, a drive force of the motor 104 is transmitted to the gear 103, the ink sheet winding gear 109 and the roller shaft drive gear 110 via the plurality of middle gears 111. At this occasion, the drive force is transmitted from the gear 103 to the roller 102 via the oval shape portion 102b and the shaft portion 102a of the roller 102. Thereby, the roller 102 is rotated while being supported by the bearing members 107 and 108. As a result, sheet (not illustrated) is fed at constant speed. Further, the drive force is also transmitted from the ink sheet winding gear 109 to an ink sheet winding roller shaft (not illustrated) and therefore, ink sheet is wound. Further, the drive force is transmitted from the roller shaft drive gear 110 to the roller shaft 113 and therefore, sheet (not illustrated) is carried in a sheet charging direction or a sheet discharging direction.
According to the thermally transcribing printer of the background art shown in FIG. 17 through FIG. 19, in order to connect the roller 102 and the gear 102 so as not to be rotated idly, it is necessary to form the oval shape portion 102b or a D-shape portion at the outer side of the shaft portion 102a of the roller 102 by machining requiring a time period in working. Therefore, there poses a problem that part cost becomes expensive.
Further, according to the structure disclosed in JP-UM-A-61-132344, mentioned above, it is necessary to provide the pin inserting hole at the rotating shaft in order to connect the rotating shaft and the roller (roll main body) so as not to be rotated idly and therefore, there poses a problem that a time period is taken in working to bore the rotating shaft.